Francis o



- UNITED STATES PATENT OFFICE.

FRANCIS O. BLACKW'ELL, OF NEIV YORK, N. Y

ELECTRICAL RESISTANCE.

SPECIFICATION forming part of Letters Patent No. 408,647, dated August 6, 1889. Application filed June 5, 1889. Serial No. 313,181. (No model.)

To all whom it may concern.-

Be it known that I, FRANCIS O. BLACKWELL, a citizen of the United States, residing at New York, in the county of New York, State of New York, have invented certain new and useful Improvements in Electrical Resistances, of which the following is a specification.

My invention relates to resistances to be inserted in an electric circuit for regulating the amount of current passing therethrough. It is of the type of resistance formed by placing a series of plates of iron or steel in contact with one another and providing a movable contact that passes over the edges of the plates to bring more or less of them into circuit.

It consists in details of construction set forth in the following specification and claims.

In the accompanying drawing, A represents a circular box of cast-iron divided into two sections. Within each of these sections a box or packing B, of earthenware, asbestus, or similar non-conductin g and non-combustible material, is placed. Within this are packed a series of sheet-iron plates 0, having their upper edges projecting slightly above the insulation B. In the center of box A is pivoted an arm 1), extending radially in opposite directions and terminating at its ends in spring contact-pieces E, which move in opposite directions and are adapted to ride on the surface of plates 0. On the spindle carrying the arm D is a small pinion F, and a rack G is fixed in bearings, so as to slide diametrically across the box and engage with the pinion F. The rack G may be moved manually in each direction, or it may be actuated automatically in one direction by the eoil-spring H. The center of the arm D, at which point it is pivoted, is insulated from the cast-iron box A; or the two ends may be each insulated from the center of the arm. The opposite ends of the circuit are connected, respectively, to the diametrically opposite ends of the two halves of the box, so that they may be in series with each other. If desired, they may also be put in multiple are by an obvious method of connection. It will be apparent that this box is complete in itself, the rotating arm being journaled 011 a part of the frame made by the cast-iron box A, and the rod G also having its bearings on the same frame. By this arrangement a very compact form is given to the box, which, together with its completeness, renders it especially useful for street-railway work.

In order that the plates 0 may readily conform to the circular shape of the box,I insert at intervals triangular pieces K, it being essential that a uniform contact-pressure between the plates should be maintained throughout the series. It is evident that only apart of the series of plates maybe used, and that the circular series need not be complete, as shown, the term being used to indicate that the plates are arranged in the are of a circle.

It has heretofore been found difficult to attain the proper movement for a pivoted contact-arm, due to the lateral displacement of any connecting-rods attached directly to the arm. By providing a pinion and rack moving directly in a straight line the contact can be operated by a short substantially straight movement of the rack. It is obvious that the rack may be replaced by any other form of mechanism for converting the rectilinear motion of the actuating device into the rotating movement of the contact-arm.

What I claim as new, and desire to secure by Letters Patent, is

1. In an artificial resistance, the combination, with an inclosing-box, of a circular series of plates in contact with one another, and one or more filling-pieces to compensate for the difference between the internal and external peripheries of the series.

2. In an artificial resistance, the combination of a box or frame containing a circular series of plates in contact with one another, and an arm journaled to said frame and provided at its extremity with a contact piece adapted to move over the surface of the plates.

3. The combination, in an artificial resistance, of a circular series of plates, an electrical connection to one end of the series, and a contact-arm concentric to the plates and provided with an electrical connection, whereby the current may pass along said arm through more or less of the series of plates.

4.. The combination, with a series of resistance-plates, of a box or frame therefor, and a contact-arm for the said plat-es pivoted to the said frame.

5. The combination, with a series of resistanceplates, of a pivoted contact-arm therefor, a pinion or wheel. concentric to the said arm, and an. actuating device therefor moving substantially in a straight line.

6. The combination, with a series of resistance-plates and a centrally-pivoted contactarm, of an aetuating-rod for said arm, moving substantially in a straight line longitudinally with its axis.

7. The combination, with two series of resistance-plates oppositely placed, of an intermediate pivoted contactarm having a moving connection at each end with the two se ries of plates, respectively.

8. The combination, with a series of resistance-plates, of a frame or support therefor, having a cont-act arm pivoted to the said frame but insulated therefrom, and an elec trical connection to the series of plates along said arm.

9. The combination, with a circular series of resistance-platcs, of a pivoted contact arm, aninclosing-case insulated from said arm, an electrical connection to one end of the series of plates, and the opposite electrical connection extending along the said arm.

10. The OOll'llJlllfthlOll of two circular series of resistance-plates and an intermediate pivoted contact-arm connecting its opposite ends with the two series of plates, respectively, an inclosing box or frame for the plates insulated from the said arm, an electrical connection to each of the said series of plates, and an intermediate electrical connection between them through the said contact-arm.

11. In an electrical resistance, the combination of inclosing-box A, insulating material 1-3, the centrally-pivoted contact-arm 1), having at its outer end a contact-1i iece E, and an electrical connection therefrom extending radially toward a lixed center.

12. The combination, in an electrical resistance, of the box or support A, insulation 13, plates C, pivoted ctmtact-arm l), a wheel concentric with. the contact-arm, and a longitudinally-moving actuating device for the said wheel.

13. The combination, with a series of resistance-plates, of an inclosing box or frame therefor, a pivoted contaetarm, and longitinlinally-moving device for actuating the said arm.

1-l-. The combination, in an artilicial resistance, of a series of resistance plates, and a contactpioce adapted to move over the surface of said plates, with an actuating device for positively moving the contact-piece in. one direction and a spring for moving it in the reverse direction, as described.

15. In an artificial resistance, the conibination of a box or frame, a series of resistance plates, and a pivoted contact-arm, with an act uating device for moving the arm in one direetion and a spring to automatically restore the arm to its normal position.

if). The combination of a plurality olf re sistances and a corresponding set of contactpieces for cutting the resistances into and out of circuit, with a common actuating device for moving the contact-pieces in. one direction and a spring for moving them in the reverse direction.

17. The combination of two series of radially-arranged resistance-plates, with two corresponding centact-pieccs adapted to sweep over said series of plates, respectively, and a common actuating device therefor, whereby the plates are cut into and out of circuit simultancously.

18. The combination of two series olf re sistance-plates arranged adjacent to each other and connected to the line-cirtmit at their opposite ends, respectively, with two contacts sweeping over said resistances and moving in opposite directions and a connnon. actuating device for both contacts, substantially as described.

ll The combination of a box or frame divided into two sections, a series of resistanceplates in each section, and a connection with an electric ci rcn it situated. at opposite ends, re spectively, ot' the said series of plates, and contact-pieces for cutting said resistances into and out of circuit.

20. The combination of a box or frame, a circular series of resistance-plates, a pivoted contact-man, an actuating device therefor moving in substantially a straight line, and mechanism within the box for converting the rectilinear motion of the actuating device into the circular movement of the arm.

21.. The combination of a series of radiallyarranged resistance-plates with a contact arm adapted to sweep over said plates, pivoted substantially at the center from which the plates radiate.

22. The combination, with a curved series of plates forming an electrical resistance, of a concentric contact-arm moving over the plates in connection. with their edges, and an operating device cxtemling therel'rmn in dianietrically-oppositc directions.

2 3. The combination of a resistance composed ol. a series of plates in contact with one another, an arm or traveler for the plates passing along their contact-surlfaces, and an actuating device for said arm extending therefrom in. opposite directions.

2 The combination, with a curved series of plates forming an artilicial resi lance, ol a concentric arm or traveler passm g over their contact-surfaces and a positive operating-connection in engagement with said arm or traveler.

25. The combination, with a series of plates torining an artificial resistance, of a centered arm or traveler assing over their contactsurlaces, a wheel conctmtriewith said arm, and a longitudinal, operating-connection in migagemcnt with said wheel.

26. As an article of manufacture, an elecing, with a series of metallic plates inclosed 1o trical resistance consisting of an inclosingtherein, and a movable contact-piece having box having an insulating fire-proof lining, bearings 0n the inclosing-box but insulated With a series of metallic plates inclosed theretherefrom.

5 in,and a centered contact-arm or traveler piv- Signed this 22d day of May, 1889.

oted on said box. FRANCIS O. BLACKVVELL.

27. As an article of manufacture, an elec- \Vitnesses: trical resistance consisting of an inclosing- G. RENAULT, box having an insulating and fire-proof lin- ALEXANDER MOFFAT. 

